Method and apparatus for cleaning



May .11, :1937. K. J. R. R BERTSQN I 20359 ux'rnon AND APPARATUS FORCLEANING ARTICLES, PARTiCULARLY METALLIC GOODS Original Filed Aug. 25,1928 3 I a 4i? i; f 50 1? 2 1 5- 17 12 L t.v 13 31 A TTORNEY R issues"May 11, 1937 PATENT OFFIC METHOD AND APPARATUS FOR. CLEANING ARTICLES,PARTICULARLY METALLIC" GOODS Kenneth James Rennie Robertson, London,Eng-. land, assignor, by mesne assignments, to E. I. du Pont de Nemours& Company, Wilmington, Del., a corporation of Delaware Original No.1,905,968, dated April 25, 1933, Serial No. 302,038, August 25, 1928.Application for reissue June 15, 1936, Serial No. 85,442. In

reat Britain June 13, 1928 16 Claims.

This invention relates to methods and apparatus for cleaning articles,particularly metallic goods.

The main object of the present invention is to provide a method andapparatus for cleaning articles, more especially metal articles andcastings, wherein .the whole surface of the articles will be subjectedto solvent action, preferably combined with a scrubbing or washingmovement, and a second object is to provide a cleaning plant from whichthe articles emerge in a dry condition. A further object is to providefor the continuous use of a comparatively small body of solvent byre-clrculating the solvent through the cleaning plant and extracting anydissolved grease'and dirt after its Contact with the dirty articles,

whereby a supply of clean vapor to the plant is obtained; 1

A still further object is to prevent losses of the highly volatilesolvents employed by leakage to atmosphere and thereby. render operationof plant according-to thein-vention economical.

In accordance with the present inventiona method of cleaning greasy'oroily articles consists "inimmersing hem or moving them into a bodycf'solvent vapor and allowing the article to remain in the vapor until aquantity of solvent vapor has been condensed upon the article sufficientto remove the oii and grease therefrom. In order to effect thecondensation, the article should, of course, be substantially colderthan the solvent vapor so thatthe desired amount of cohdensation of thevapor will take place. More.-

"- over; after "the oil and grease have been thus removed by thecondensation of vapor, the article should be again moved out of thevapor bath'into the atmosphere, so as to avoid contacting the articlewith any liquidcontaining' oil or grease.

To obtain continuous cleaning the articles are preferably traversedthrough a bath of the vapor solvent, the grease charged condensate ofwhich is regenerated and resupplied to the bath as clean vapor afterextraction of the grease, and the bath is thus maintained charged withthe clean vapor solvent necessary for effective cleaning of thearticles.

The solvents used are preferablythose whose vapors are heavier than airand such as will readily remove grease, wax or oils from metallic goodswithout any chemical effect on those goods, and the employment ofsuchvapors permits of an open trough or chamber'being used, the vaporlying near the bottom of the trough or chamber, and to apredeterminedheight controlled by the admission of vapor, and ifdesiredalso by refrigerating means located in the upper zones of the trough orchamber which cause any vapor rising to their vicinlty'to condense andfall to the base of the chamber. I 5

Preferred apparatus for cleaning greasy articles according to theinvention, includes a. bath of vapor solvent, a conveyor traversingarticles through such bath, and regenerating stills extracting thegrease charged condensate from the bath, regenerating and maintainingthe bath charged with clean vapor through inlets connecting the bathwith the stills.

Preferably the inlets are dispwed so as to produce a circulatingmovement of the vapor in the nature of a convection current, and inaddition such inlets are preferably duplicated or multiplied, each setof inlets having an associated regenerating apparatus so that oneapparatus may be disconnected and cleaned by the ejection of accumulatedgrease and dirt, while the other supplies the bath with the regeneratedclean vapor.

At the bottom of the bath outlets are provided ,for collecting thecondensation products and these .outletsare connected'to regeneratingapparatus forreforrmng the-vapor from the condensation products, theregenerators being preferably' directly, connected to the vapor'lnletsto the trough to form a closed cycle and so that a continuous supply ofvapor is assured.

A cleaning plant according to the invention may be automaticallycontrolled by thermostats assowith "the refrigerating zones aforesaid oralternative thereto.

The invention will be further described with rei'erenceto theaccompanying sheet of explanatory drawings which illustratesdiagrammatically by way of example a preferred form of apparatus forcarrying the invention into effect, and in which:

Fig. 1 is a transverse section of the apparatus showing the conveyorfeed for the articles to be cleaned and the disposition with regardthereto; and I Fig. 2 is a section on the line 11-11 of Fig. 1

showing the vapor circuit and the relative arof the vapor inletsrangement of the cleaning section of the cone 'veyor.

Referring now to the drawing I is a bath in the form of a U-shaped ductin which is disposed a conveyor 2, mounted on feed rollers 3 andpreferably adapted for the continuous feeding of a succession of thearticles 4 to be cleaned, which are shown suspended from the conveyor 2and whichdependent on the form of the articlemay either be carried inbaskets mounted on the conveyor or suspended direct therefrom by meansof hooks. The articles 4 are preferably at normal or room temperature.-

In the example illustrated the conveyor 2 is moving in acounterclockwise direction and the articles 4 about to be cleaned enterthe bath at 5 and are discharged at 6 after passage through the cleaningzone I of the bath I cleansed as required by the removal of any greaseor dirt which adhered to their surfaces.

I 8 represents vapor inlet nozzles to the cleaning zone 1, which aredisposed in the vicinity of the feed conveyor 2 and the vapor-at asomewhat elevatedtemperatureissuing from the inlets 8 impinges on thegreasy articles 4 to be cleansed, which, due to their lower temperaturecause condensation of the vapor on their surfaces, this condensate afterdissolving the superficial grease and dirt carried by the articles 4falling to the bottom 9 of the bath I from whence it is withdrawnthrough waste pipes such as I0 and II and regenerated as desired.

The vapor circuit is illustrated in Fig. 2 and it will be seen that thewaste. pipes III and II communicate with stills I2 and I3 respectivelyin which the condensed vapor is regenerated by being boiled under theinfluence of sources of heat I4 and I5 disposed in association with eachof the stills I2 and I3, the regenerated vapor passing through conduitsI8 and I1 and the nozzles B to the cleaning zone I and the collectedgrease and dirt being discharged from the bottom of the stills I2 andll- -say at intervals through conduits I8 and I9 provided with suitablevalves or taps adapted to regulate the discharge.

As has already been mentioned the vapors utilized in the bath I arepreferably those heavier than air, and such as will readily removegrease, wax or oils from metallic goods without havingany chemicaleffect on the goods, but even with heavier than air vapors, an excessiveregeneration from the stills I2 and I3 taking place, a certainproportion of the vapor in the bath I would leak to atmosphere unlessspecial provision'were made for its prevention. Accordingly in the upperzones' of the bath I a series of cooling pipes are disposed around theinner surface of the bath I through which pipes refrigerant ispreferably conveyed, so that on the vapor reaching the upper zones ofthe bath, that is in the vicinity of the cooling pipes 20, condensationis effected and the vapor falls to the base 9 of the bath and isconveyed through the waste pipesv III, I I, to one or other of theregenerating stills I2 and I3.

Where desired, control of the regeneration in.

, the stills I2, I3, may be effected by means of a thermostat such as23, which may, if desired, replace the series of cooling pipes 20, ormay be used in addition thereto, such thermostat 23 being arranged sothat when subjected to the influence of the warm vapor it operates toclose one of the waste pipes such as II and a vapor supply pipe such asIT by valves, 3| and and simultaneously cut off the supply of heat tothe corresponding still I3 by the closing of valve 25, so

that the condensate is removed from thebath only through the waste pipeIII and regeneration only continued in the still I2 until desiredcondi-. tions are restored, whenthe thermostat 23 will reopen the wastepipe I I, the vapor supply pipe I1, and simultaneously supply heat tothe still I3,

thereby commencing regeneration of the vapor therein.

The thermostat 23 is preferably disposed somewhat above the cleaningzoneI, say in the entry I 5 or the exit 6, and remote from the influence ofthe cooling pipes 20, providing a refrigerating 'zone therefor. I y,

A particular form of still utilized is illustrated in Fig. 2 of thedrawing and is rovided with a convex base 24 below which is disposed asuitable source of heat for example, a gasburner I4 or I 5, the supplyof gas ,to which may be under control from the thermostat 23 by means ofa diaphragm valve 25, and the still being provided with a dischargeconduit such as I8 or I9 for the collected grease and dirt.

In operation and using as the cleansing medium or solvent, saydichlorethylene having a boiling point in the neighborhood of 125 theStills are arranged to deliver the vapor through the inlets 8 at atemperature of say 120 F. and the articles to be cleaned possessing anormal temperature of say 60 F. are fed to the conveyor 2 at 5 andconveyed into the cleaning zone I,

where, by reason of their relative coldness, condensation of the solventvapor is effected on their surfaces, whereby the grease and dirt coatingis dissolved off in solution which-as liquid-falls to the'b ase 9 of thebath and passes through the 'waste pipes Ill and II to the stills I2 andI3 and thearticles are dried by the heat from the condensing vapor.

Regeneration is effected in the stills under control of the thermostat23-, the regenerated vapor being supplied in the cleaning zone I throughthe vapor inlets 8 and the residue grease and dirt remaining in the baseof the stills I2 and I3 from" whence it is collected as required.

Where desired, the conveyor 2 may be arranged so that the articles 4after cleaning are passed through a chamber in which hot air iscirculated,

in order to remove the last traces of solvent, .or alternatively aseparate conveyor may be used for this purpose. Q

An alternative method of regenerating the vapor and simultaneouslyseparating the collected grease and dirt is illustrated in the dottedlines in Fig. 1 wherein the base-9 of the bath l arev shown a series ofheating pipes 26 through which may be passed steam or other mediaadapted to maintain the pipes at a temperature suflicient to effectvaporization of any condensed liquid falling in their vicinity, suchtemperature depending on the particular vapor or solvent used, and beingconveniently controlled by suitable thermostats.

It may be .iound preferable to arrange the series of refrigerant coolingpipes 20, so that-they are hingedly secured to permit of the opening ofthe bath to atmosphere at the entrygand the exit '6 being suitablyregulated, while although the apparatus shown includes two stills I2jandIt for regenerating the vapor, more of these stills may be provided ifdesired, each preferably under thermostatic control,.so that individualstills may be dismantled or cleaned while the apparatus remains inoperation.

The method of and apparatus for cleaning articles according to theinvention assures complete removal of all grease from the articles,

By'ensuring that the articles entering the bath are in a relatively coldcondition while the vapor is at a moderately high temperature the heatliberated by the solvent condensing on the surfaces 1 of the articlesraises their temperature, thus softening any grease ontheir surfaces andrendering it more easily soluble whilst evaporation of any condensedsolvent is ensured prior to the articles leaving the bath so that theyissue in a cleaned dry condition. 1

Further the vapor treatment according to the invention permits of thevapor penetrating to the surface of the articles to be cleaned prior toits condensation, thereby effecting an exceptionally rigorous detergentefiect with consequent complete removal of any grease and dirt fromtheir surfaces.

Although the invention has been described with more particular referenceto the treatment of metallic articles, it should be understood that itis also applicable to the cleaning of fabrics, garments, wool and othersimilar materials.

In view of the description of the invention, it will be apparent that animportant advantage of the invention consists in the simplicity of theoperation whereby the object to be cleaned is moved into the solventvapor bath through the open atmosphere without having to attend to theremoval of covers of apparatus and without hav-' ing to wait for thesolvent to be generated. The bath of solvent vapor is continuouslymaintained and the objects to be cleaned are directly moved into itthrough the open atmosphere, and allowed to remain until enough solventhas condensed to 40 remove the oil and grease, and then the objects aredirectly moved out again through the open atmosphere. The simplicity andease of operation are characteristic of this invention. The

objects are not left with a filmof oil or grease.

which would occur if they were directly immersed into a body of cleaningliquid. What I claim is:

1. A method of removing oil and grease from an object which consists ingenerating a solvent vapor, collecting said solvent vapor in a containeropen to the atmosphere, moving said object into said solvent vapor bath,allowing the object to remain in said solvent vapor bath untilsufiicient solvent vapor has been condensed thereon by reason cf thedifference in temperature between said object and said vapor to removethe oil and grease therefrom, and thereupon moving said object out ofsaid vapor bath.

2. A method of removing oil and grease from an object which consists ingenerating a solvent vapor, collecting said solvent vapor in a containeropen to the atmosphere, moving said object into 1 said solvent vaporbath, and allowing said object to remain in said bath as long as thereis a substantial diiference in temperature between said bath and saidobject, whereby solvent vapor is condensed on said object and the oiland grease removed thereby.

3. A method of removing oil and grease from an object which consists ingenerating a solvent vapor, collecting said solvent vapor in a containeropen to the atmosphere, moving said object into said solvent vapor bath,allowing said object to remain in said bath until sufiicient solventvapor has been condensed thereon by reason of the condensing vapors atthe to prevent their escape, moving the said object means for 'heatingdifference in temperature between said object and said vapor to removethe oil and grease therefrom, and thereupon moving said object out ofsaid vapor bath into the atmosphere.

4. A method of removing oil and grease from the surfaces of an objectwhich consists in gen-' erating a solvent vapor, collecting said solventvapor in a container open to the atmosphere, moving said object intosaid solvent vapor bath, said solvent vapor bath being maintained withina fixed space, allowing said, object to remain in the bath untilsuiiicient solvent vapor has been condensed thereon by reason of thediiference in temperature between said object and said vapor to removethe oil and grease therefrom, and zhzlgeupon moving said object out ofsaid vapor 5. A method of removing oil and grease from an object whichconsists in generating a solvent vapor, collecting said solvent vaporin'a container open to the atmosphere, moving said object from the openatmosphere into said solvent vapor bath, allowing said object to remainin said bath until suflicient solvent vapor has been condensedthereon byreason of the difference in temperature between said object and saidvapor to remove the oil and grease therefrom, and thereupon moving saidobject out of said vapor bath and into the atmosphere.

6. A method of removing oil and grease from an object, consisting inboiling a grease solvent in a vessel open to the atmosphere so that avolume of solvent vapor is maintained'in the vessel, open top of thevessel into the vapor and allowing it to remain there until the oil andgrease have been removed by the condensation of the solvent, and thenmoving the object out of the vapor into the atmosphere again.

7. A method of removing oil and grease from an object, consisting inboiling a grease solvent whose vapors are heavier than the atmosphere,

in a vessel open to theatmosphere, so that a volume of solvent vapor ismaintained in the vessel, condensing vapors at the open top of thevessel to prevent their escape, moving the said object into the vaporand allowing it to remain there until the oil and grease have beenremoved by the condensation of the solvent, and then moving the objectout of the vapor into the atmosphere again.

8. A degreasing apparatus comprising a vapor chamber having inlet andoutlet openings toward the top thereof, a grease solvent liquid tank,said tank to vaporize liquid solvent contained therein, a vapor conduitconnecting said tank with said chamber, cooling coils arranged at theupper part of said chamber for condensing the vapor therein, a drainpipe connecting said chamber with said tank and a conveyor arranged tocarry, articles through said chamber and expose them to the condensingvaporous solvent.

chamber through the inlet and outlet opening passages. I

10. A combination of apparatus for cleaning greasy articles comprising atrough having an inlet and an outlet open'to the atmosphere, coolingmeans in combination with the trough adjacent said inlet and outlet, thebody of the trough being arranged at a level below said inlet andoutlet, an endless conveyor entering the trough from a level above saidinlet and adapted to convey articles through the trough, a still forproducing solvent vapors, means for feeding vapors from the still withinthe trough above the line of travel of the conveyor and means forremoving grease and dirt from the bottom of the trough, said inlet andoutlet being arranged with respect'to the body of the trough so thatvapor heavier than air will be retained in the body of the trough,wholly covering the portion of the conveyor therewithin, and have itsupper level below the inlet and outlet openings. l

11. Apparatus for cleaning articlescomprising a trough substantially Ushaped inv form, the

body of the trough being the lowermost portion" ing means for preventingescape of vapor from the trough to the outer atmosphere, and means forcontrollingthe level of the vapor within the trough.

12. A comblnationoi apparatus for degreasing articles comprising atrough, U-shapedin form, an inlet to and an outlet from said trough opento the atmosphere, cooling means for preventing escape of vapor from thetrough, to the outer atmosphere, the body of the trough comprising thebottom portion of the U, means for evaporating a liquid solventexternally of said trough, a nomle leading from said means to the upperportion of the body of the trough, a drain from the bottom of the bodyof the trough leading to said means, and means for lowering articleswithin the v trough and withdrawing them therefrom.

13. A combination ofvapparatus of the characterjdescribed comprising atrough having an inlet and ,an outlet open to the atmosphere and at alevel above the body of the trough means for producing solvent vaporsexternally of the trough, nozzles, for feeding vapors from said meanswithin and at the uppermost portion of the body of the trough, coolingmeans for preventing escape of vapors to the outer atmosphere and aconveyor for carrying articles to be degreased traversing the body ofthe trough beneath said nozzles.

14. A degreasing system having a trough at a certain level, an inlet toand an outlet fromsaid trough open to the atmosphere at a level abovethe trough, means for generating solvent vapors and feeding it withinthe trough, means comprising condensing coils to confine the vaporswithin the trough and above the body thereof but below the inlet andoutlet, means for returning used solvent to said vapor generating means,and means for conveying articles to be dcgreased.

within the trough.

15. A combination of apparatus of the character described comprising atrough'having an inlet and an outlet, means for conveying articleswithin the trough and removing them therefrom,

means comprising a still for generating a vapor adapted to dissolvegrease, means for feeding the vapor within the trough, meansfor removingcondensate and residue from the trough to said still for regeneration,said trough having cooling means for preventing escape of vapor throughsaid inlet or outlet, and means for retaining the level of the vaporbelow the inlet and outlet.

16. A combination of apparatus of the character described'having atrough, a vapor generator apart from said trough, an arrangement ofnozzles. for feeding vapor from the generator to the upper portion ofthe trough, means for withdrawing liquid and residue from the lowerportion of the trough to the generator, one portion of the troughadapted to be completely filled with vapor from top to bottom, thetrough having an extension open to the atmosphere, cooling means forconfining the vapors to the trough and means for traversing articles tobe' degreased within the trough betweenthe levels at which vapor isadmitted and liquid and residue removed.

KENNETH JALJES RENNIE ROBERTSON.

